While society sees the impact of 5G through new, real-time consumer entertainment and business innovation, operators of telecom data centers are experiencing a very different impact. The need to make 5G responsive and reliable is driving data center capabilities out of central facilities, a trend that raises the requirements for battery backup.
According to the GSM Association, the fastest 5G networks are expected to be at least 10 times faster than 4G LTE. This higher bandwidth not only supports faster download and upload speeds for applications and data but also expands the capabilities for IoT applications connecting large numbers of sensors across homes, cities, and industry.
The high 5G speeds also lower signal latency between data centers and endpoints (user devices and IoT nodes), which makes more robust real-time applications, such as autonomous vehicles and remote surgery, possible. As a de facto platform for IoT, 5G will open up new levels of machine-to-machine communications for many computing use cases, which will cause demand to skyrocket.
To maintain high throughput and low latency, telecoms are migrating 5G data storage and processing closer to end users and IoT nodes, accelerating the proliferation of edge data centers. According to Gartner, edge computing (processing outside a traditional centralized data center or cloud) will account for 75% of enterprise-generated data by 2025, up from just 10% in 2018.
As edge data centers pick up the computing load for 5G-driven applications, they will require an evolution in robust UPS systems to safeguard uptime and ensure mission critical connectivity and response time. Operators of edge data centers will need to examine battery backup solutions according to the following criteria.
- Smaller size and weight to adapt to a wide range of edge data center environments — from server rooms to containers to closets.
- Safe operation to ensure edge data centers are no threat to the facilities and employees working around them.
- High reliability and low maintenance requirements to ensure continued operation no matter where the data center is located.
- Sustainability, as green batteries are essential due to the escalating number of edge data centers driving up battery backup deployments.
Higher Power Density
For decades leading up to the 5G era, the industry has relied on lead-acid batteries for data center backup. This familiar technology was adequate when data centers were centralized, controlled environments. Being a very mature technology, lead-acid batteries have a relatively low up-front costs but high maintenance requirements.
Compared to centralized facilities, edge data centers have even less space for battery backup, yet the demands of 5G services dictate the need for high-performance, power-hungry servers. These increasing demands for high power and a small footprint are making newer high-density battery technologies, especially lithium-ion and nickel-zinc (NiZn), more competitive. NiZn batteries, for example, have the highest power density and can provide the same backup capacity as lead-acid batteries in half the footprint and weight.
Because edge data centers will become widespread and are often located in facilities close to employees and the public, safety is another driving issue. To compare the safety of technologies used in energy storage systems, engineers can consult NFPA 855 Standard for the Installation of Stationary Energy Storage Systems (ESS), which covers energy storage installations like battery backup systems.
NFPA 855 sets the storage capacity threshold for ESS battery chemistries beyond which those systems must meet NFPA 855 requirements to ensure safe operation. For lead-acid and NiZn, this threshold has been set at 70 kWh of stored energy. In contrast, the thresholds for Lithium-ion batteries have been placed at just 20 kWh. For a given power output, these technologies are likely to face additional infrastructure upgrades and safety systems that increase their footprint and upfront costs.
To assess safety once in operation, NFPA 855 references the UL 9540A Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems. Additionally, the safety-driven requirements of NFPA 855 for placement of lithium-ion energy storage may increase facilities costs. The cell-level safety of NiZn batteries is a clear advantage, especially in space-limited edge installations where additional safety measures are not possible and extreme edge environments can vary widely.
When it comes to reliability, all three technologies have specified operating ranges and product lifetimes. While they are initially more expensive, both lithium-ion and NiZn battery backup systems have from two to three times the useful operational life of lead-acid batteries. This not only enhances reliability, but it also minimizes the operating costs involved with one or two battery replacement cycles.
Another key parameter of reliability is battery string operation. When a lead-acid or lithium-ion battery cell fails, it creates a high impedance or an open circuit that halts string operation. A weak or depleted NiZn cell, on the other hand, remains conductive, allowing the string to continue operating. In addition, NiZn battery strings tolerate string imbalances better and maintain constant power output at lower states of charge and health than the other technologies.
Finally, NiZn battery systems have an operating temperature range greater than lead-acid and lithium-ion systems, which also boosts reliability while lowering facility cooling requirements.
Sustainability is no longer optional, it has become an obvious priority for data center operators. While the lead-acid manufacturing industry does a good job of promoting the high rate of recycling for lead-acid batteries, they contain lead and other hazardous materials that create a highly pollutive and hazardous recycling process. In fact, environmental organizations have identified used lead-acid battery recycling as one of the world’s major pollution problem.
Lithium-ion batteries are often considered a “cleaner” option to lead-acid batteries, yet they contain rare earth elements that are highly polluting to source. The extraction of lithium alone has significant environmental and social impacts, from water pollution and depletion to toxic chemical leaching, spills, and air emissions.
NiZn chemistry is easier on the environment than lead-acid and lithium-ion batteries. The bill of material for NiZn batteries mainly consists of common, highly available, nonhazardous materials. In a recent Climate Impact Report performed by Boundless Impact Research & Analysis, NiZn batteries ranked higher than lead-acid and lithium-ion chemistries across several criteria. When compared with other battery chemistries, NiZn technology received the highest overall score of 9.4 out of a possible top score of 10.
As 5G services proliferate across society, people and businesses will come to enjoy and depend on the upcoming high performance, low-latency applications. As the key to maintaining bandwidth and latency margins, edge data centers will need to be always available to process the exploding data requirements from a constellation of end-user and IoT devices. The choice of technology for battery backup has a substantial impact on the size, safety, reliability, and sustainability of edge data centers that will make 5G play a productive role in our world.